1. Field of the Invention
Disclosed exemplary embodiment is directed to technologies that may receive a partial discharge signal of an ultra-high frequency (“UHF”) band through a sensor to measure the partial discharge and display the location where the partial discharge occurred in a power device.
2. Description of the Related Art
Partial discharges occur mostly in a case where there is a defect inside a high-voltage power device such as oil-immersed transformers, gas insulating transformers, reactors, etc. There has been conventionally suggested a technology for measuring such partial discharges, which measures the arrival time of a sound wave signal transmitted from a location where the partial discharge occurs to each of a number of sensors attached on a casing of a device-under-test (“DUT”) through the casing or insulating material, such as transformer oil, using the sensors, calculates the arrival time when the signal arrives at each sensor or difference in arrival time, and finds the location of the partial discharge from propagation velocity of an ultraviolet signal transmitted through each medium.
However, this method may evaluate the location only when there is exactly known the propagation velocity of the sound wave in the case of the DUT, a structure, or transformer oil that functions as a path through which the sound wave propagates. Moreover a measurer needs to shift the sensors on the DUT several times to exactly evaluate the location of partial discharge, and this causes the measurer burdensome.
Furthermore, some noises may intervene due to external factors such as vibration of the power device, operations of device, wind, or the like, and therefore, evaluation of the location still needs to be done by hand to raise precision and accuracy of evaluation.
There has been another conventional method that analyzes internal errors of a high-voltage power device and finds the location of a discharge. This method yields the location of a partial discharge by measuring and analyzing a partial discharge signal generated by the discharge with a partial discharge measuring device, measuring a signal from a UHF partial discharge sensor or ultrasonic sensor with an oscilloscope to calculate the arrival time of the discharge signal, and solving optimization-related problems manually or using a computer from the arrival time of the signal or difference in arrival time.
However, this method suffers from difficulties and inconvenience in arrival time calculation and calculation method because of being done manually or using oscilloscopes or computational computers, and further has a disadvantage that it is difficult for common technicians to apply this method to a discharge that experiences real time variations.
Furthermore, this method requires the measurer to manually and separately classify noises that externally come, and to use a partial discharge meter separately from the oscilloscopes, and this leads to difficulties not capable of evaluating the location of discharge simultaneously from a partial discharge signal measured at the same sensor.
Therefore, there is a need of providing a partial discharge and partial discharge location measuring device that may overcome these problems.